Frederick edward thomas and robert proudfoot lennox



(No Model.)

P. E. THOMAS & R. P. LENOX.

PNEUMATIC DENTAL PLUGGER.

No. 419,381. Patented Jan. 14,1890,

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UNITED STATES ATENT OFFICE.

FREDERICK EDWARD THOMAS AND ROBERT PROUDFOOT LENNOX, or

' CAMBRIDGE, ENGLAND.

PNEUMATIC DENTAL PLUGGER.

SPECIFICATIONfQrming part of Letters Patent No. 419,381, dated January 14, 1890.

Application filed August 5, 1889. Serial No. 319,737- (No model.)

To all whom it may concern:

Be it known that we,FREDERIoK EDWARD THOMAS, philosophical-instrument maker, residing at 7:} Jesus Lane, Cambridge, Eng land, and ROBERT PROUDFOOT LENNOX, me-

chanical dentist, residing at 59 Corpus Build ings, Cambridge, England, subjects of the Queen of Great Britain, have invented certain new and useful Improvements in Pneu matic Dental Pluggers, of which the following is a specification.

This invention has for its object an improved percussive tool to be worked by pneumatic power and applicable as a dental mallet, and forother purposes.

In order that our said invention may be more fully understood and readily carried into effect, We will proceed to describe the drawings hereunto annexed.

Figure 1 is an elevation of an apparatus constructed according to our invention. Fig. 2 is a longitudinal section. 3 is a section on the line X X, Fi 2. Fig. 4 is a section on the line Y Y, Fig. 2. Fig. 5 is a section on the line Z Z, Fig. 2. Fig. h is a side elevation of one of the parts.

A A are the two cylinders in which work the pistons B B, which are fixed to a common piston-rod C, the end of which strikes against the holder D, which carries the tool E F, being a spiral spring which tends to bring the parts D and E back again. The cylinders are connected by an air-passage, in this instance shown as formed in the piston-rod C.

G is a valve-chamber, which is connected by the flexible tube H to bellows or other airforcing apparatus. (Not shown in the drawings.) The air enters by the pipe J, passes along the radial passages K to the longitudial passages L, formed between the outside of the cylinder A and the casing of the instrument to the valve-chamber G, in which works the Valve M, sliding upon the pistonrod. The valve M is actuated by the spiral springs N N. When the parts are in the position shown in Fig. 2, air is being admitted from the valve-chamber G into the cylinder A and is tending to force the piston B forward. As soon as the aperture 0 in the casing is opened by pushing forward the tubeP by means of the serrated thumb-piece Q In the apparatus shown in the drawings the piston-rod is made hollow, so that the air from the cylinder A, as Well as that from the cylinder A, escapes through the opening 0.

As shown, the piston B forms a nut upon the screw-threaded piston-rod, and is grooved, as shown in Figs. 2 and 5, to receive a feather upon the casing, so that by turning the casing the distance of the pistons apart can be varied. By thus adjusting the distance between the pistons the length of stroke may be varied, and by altering the length of the stroke the force of the blow and the speed of working are correspondingly changed.

What we claim is 1. The combination, substantially as hereinbefore set forth, of two single-acting cylinders connected by an air-passage, a pistonrod, pistons on the rod and Working Within the cylinders, the percussive tool, and a valve controlling the admission of air to the cylinders.

2. The combination, substantially as hereinbefore set forth, of two single-acting cylinders connected by an air-passage, pistons working within the cylinders, a piston-rod on which both pistons are carried, the percussive tool, a valve interposed between the pistons and mounted on the piston-rod, and the springs interposed bet-ween the valve and the pistons.

3. The combination, substantially as-hereinbefore set forth, of two single-acting cylinders, pistons working within the cylinders, a piston-rod having a passage through it connecting the outer ends of the two cylinders, the percussive tool actuated by the piston-rod, a valve upon the piston-rod between the pistons, and springs interposed between the pistons and the valve,

between the pistons, said piston-rod being formed with a passage connecting the outer ends of the two cylinders, a valve on the piston-rod between the piston, and springs interposed between the valve and the pistons.

FREDERICK EDWARD THOMAS. ROBERT PROUDFOOT LENNOX. \Vitness'es:

A. E. KING, 11 Bond Street, Cambridge, Solz'citofis Clerk.

H. G. WEEKLEY, 3 WeZl zhigton Terrace, Holland Street, Chesterton, Omnbrir'lge, Solieitors Clerk. 

